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As many of you know, BimmerBoost user LostMarine got his 335i Steptronic transmission built by Level 10 to handle increased torque as his upgraded turbos took their toll on the stock transmission. Turn around time was surprisingly quick and should be 10 days and under for all N54 transmission builds. LostMarine had the transmission built along with upgrading the torque converter with a higher stall and the valve body. Price will vary depending on options.

In Lost Marine's words:

So here are the details I can speak of. Car runs strong, very solid and strong now. Much improved over what I can remember even when I first bought the car. Here she is as the short journey began. Luckily the car was only down for about 1-1/2 weeks

Clutches were fried in mine as you can see from this pic.

They were replaced with stronger material obviously. Now rated up to 700ft/lbs

Tq convertor was setup for mild street use and increased stall RPM by 500.

Sorry no more pics on that

VB Pressure was increased from the stock 60-70psi to 130 psi.

Pump volume was also increased in total flow from 2qt's/30 seconds to 3 qt's/30 second

All of this translates in the much stronger and firmer shifting that I have been noticing.

I have to say, for being a BMW and asking for a mild street use Transmission , Level 10 Delivers.

The higher stall has nearly no affect on the DD driving characteristics of the car. I do not feel any "slack", and had i not known the stall was increased, I could never tell.

I had planned on attaching video of the car/trans going through the gears, but the angle was way off. I attempted to have it catch the sound and speedo/Tach so you could see the correlation, along with Datalogs. The roads today were not easily manuevered though.

The stall speed of the torque converter. Basically when you step on the brake and the gas there is a stall RPM, right? Well, this RPM is now higher.

It doesn't have to do with the gas and the brakes. That would change based on your braking system. But having a higher stall does have an effect on that.

Here is a good explaination from a Ford forum:

The stall speed of a converter is determined by several things. A converter is made up of 4 parts, the front cover, stator, impeller, and rear cover. Each part has fins inside it to direct the fluid around each part and by modifying these fin's angle, it changes the stall speed. Stall speed is essentially when the engine speed and fluid speed are the same, and stall speed is NOT when you're sitting at a stop and mash the gas while holding the brake. That rpm is NOT the stall speed, that's just where the engine torque overpowers the brakes and moves the car forward.
A higher stall speed allows the engine to get into the powerband quicker, like revving a clutch and quickly slipping it. Unlike a clutch, a converter doesn't get grabby or tempermental. But a higher stall speed creates more fluid slippage inside it, creating more heat so an auxiliary trans cooler should be considered mandatory.
A higher stall speed can also take the shock out of the drivetrain when the trans shifts, making it actually easier on parts.
The stall speed can also be affected by the engine it's behind. A converter that stalls at 2000 behind a stock small block could stall at 3800 behind a big block. This is why converters should be custom made for your combination for the best performance.

Great write up! Might be the next in line for this upgrade, kind of amazing you had only 1 and half week downtime, excellent work and shows how familiar they are with the zf trans. Wouldnt oil smell burnt and be black if the clutches are gone?
You never changed the AT oil prior the failure Lostmarine?

Great write up! Might be the next in line for this upgrade, kind of amazing you had only 1 and half week downtime, excellent work and shows how familiar they are with the zf trans. Wouldnt oil smell burnt and be black if the clutches are gone?
You never changed the AT oil prior the failure Lostmarine?

He did change it once around 65k if I remember correctly...but at that point I think it was already going downhill. Only a matter of time before it went after that.

ZF trans are great. I wonder how many parts we have in common with your average domestic muscle car?

Great write up! Might be the next in line for this upgrade, kind of amazing you had only 1 and half week downtime, excellent work and shows how familiar they are with the zf trans. Wouldnt oil smell burnt and be black if the clutches are gone?
You never changed the AT oil prior the failure Lostmarine?

actually i did, at 50k miles and again around 75-80k miles. i never had any smell and not sure of oil color when they pulled it

I've heard that a properly matched upgraded torque converter can be good for nearly a half second reduction in 1/4 mile times. If they properly matched the converter to his powerband, he should be able to leave the line under very high boost.